The invention relates to an automatically opening and closing combined open-ended spanner and rapid screwing tool having a ratchet action, which is equipped with an integrated locking element and adjusting system. The ratchet-like wrench, or automatic wrench has an auxiliary assembling device and interchangeable, spanner-width inserts for each particular wrench size. As a result, it is extremely versatile and particularly easy and convenient to handle upon tightening and freeing fastening elements, preferably hexagonal-head bolts and hexagonal nuts, without withdrawal, repositioning or removal of the wrench during a gripping or screwing action and once it has been fitted.
DE-PS 449510 discloses a wrench of the kind described above, in which the return spring located in the fixed jaw acts directly on the aperture-side lever arm of the wrench handle, so that the same actuates the movable jaw in such manner that it operates similarly to pincers on the bolt or nut element which is to be freed or tightened. This pincer-like action of the movable jaw has the disadvantage that the fastening element, in the form of the nut or bolt head, which is to be freed or tightened is exposed to a comparatively high degree of wear during the ratchet-like take-up displacement of the tool, so that the edges of the fastening elements may be damaged, after repeated application of the wrench, to such a degree that the application of a standard ring spanner is no longer possible. On the other hand, the operating surfaces of the wrench also undergo a comparatively high degree of stress, thereby adversely affecting their durability. Another disadvantage of this known wrench is to be seen in that the return spring acts on the pivotable jaw with a very large leverage in the ratchet position of the wrench, so that the ratchet action may, as a rule, be brought to bear effectively only if the handle is made to follow on positively and at comparatively high speed. Furthermore, this known ratchet-like wrench is constructed with a comparatively massive spanner head and is thus comparatively unwieldy so that it has not hitherto gained acceptance in this form of construction.